Adaptive waveform selection in wireless communications

ABSTRACT

Systems and methods of wireless communication in which wireless devices are adapted to implement adaptive waveform selection are disclosed. For example, operation according to embodiments may provide for use of a waveform design that minimizes peak-to-average power ratio (PAPR), such as single-carrier frequency division multiplexing (SC-FDM), as well as a waveform design that provides higher spectral efficiency, such as orthogonal frequency division multiplexing (OFDM), for scenarios that are not power-limited and the higher PAPR is acceptable. Adaptive waveform selection may be based implicitly on one or more parameters or may be based on explicit signaling. Adaptive waveform selection may be utilized with respect to initially establishing a communication link and/or with respect to an established communication link.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/359,226, entitled, “ADAPTIVE. WAVEFORM SELECTION IN WIRELESSCOMMUNICATION”, filed on Nov. 22, 2016, and claims the benefit of U.S.Provisional Patent Application No. 62/374,473, entitled, “ADAPTIVEWAVEFORM SELECTION IN WIRELESS COMMUNICATIONS,” filed on Aug. 12, 2016,the disclosures of which are hereby incorporated by reference herein intheir entirety as if fully set forth below and for all applicablepurposes.

TECHNICAL FIELD

Aspects relate generally to wireless communication systems, and moreparticularly, to adaptive waveform selection in wireless communicationsystems. Certain embodiments of the technology discussed below canimplement adaptive waveform selection, such as to provide dynamicselection between use of SC-FM and OFDM for the communication signalstransmitted by one or more wireless devices, to use a most efficientwaveform for communication.

INTRODUCTION

Wireless communication networks are widely deployed to provide variouscommunication services such as voice, video, packet data, messaging,broadcast, and the like. These wireless networks may be multiple-accessnetworks capable of supporting multiple users by sharing the availablenetwork resources. Such networks, which are usually multiple accessnetworks, support communications for multiple users by sharing theavailable network resources.

A wireless communication network may include a number of base stationsor node Bs that can support communication for a number of userequipments (UEs). A UE may communicate with a base station via downlinkand uplink. The downlink (or forward link) refers to the communicationlink from the base station to the UE, and the uplink (or reverse link)refers to the communication link from the UE to the base station,

A base station may transmit data and control information on the downlinkto a UE and/or may receive data and control information on the uplinkfrom the UE. On the downlink, a transmission from the base station mayencounter interference due to transmissions from neighbor base stationsor from other wireless radio frequency (RF) transmitters. On the uplink,a transmission from the UE may encounter interference from uplinktransmissions of other UEs communicating with the neighbor base stationsor from other wireless RE transmitters. This interference may degradeperformance on both the downlink and uplink.

As the demand for mobile broadband access continues to increase, thepossibilities of interference and congested networks grows with more UEsaccessing the long-range wireless communication networks and moreshort-range wireless systems being deployed in communities. Research anddevelopment continue to advance wireless communication technologies notonly to meet the growing demand for mobile broadband access, but toadvance and enhance the user experience with mobile communications.

BRIEF SUMMARY OF SOME EMBODIMENTS

The following summarizes some aspects of the present disclosure toprovide a basic understanding of the discussed technology. This summaryis not an extensive overview of all contemplated features of thedisclosure, and is intended neither to identify key or critical elementsof all aspects of the disclosure nor to delineate the scope of any orall aspects of the disclosure. Its sole purpose is to present someconcepts of one or more aspects of the disclosure in summary form as aprelude to the more detailed description that is presented later.

Attention has been given to utilizing higher frequency carriers forenabling higher data rate communications (e.g., gigabit data rates) dueto the availability of large amounts of bandwidth in the higherfrequencies. In particular, millimeter-wave wireless communicationsystems (e.g., operating at 28 GHz, 60 GHz, and greater) have thepotential of providing much higher data rates compared to systemsoperating in the sub-6 GHz frequencies. Moreover, there remainsavailability of large contiguous spectrum in these bands in many regionsand jurisdictions.

The use of high frequency carriers, such as millimeter-wave, in wirelesscommunication systems is not, however, without challenges. For example,millimeter-wave communications suffer from very high attenuation of thetransmitted signal as compared with sub-6 GHz signal transmissions.Moreover, millimeter-wave signals are highly susceptible to blockage(e.g., due to obstacles, such as buildings, foliage, terrain, etc., inthe signal path) due to the small wavelength of the signals.

Although beamforming might be performed (e.g., at Tx and/or Rx antennas)in an attempt to mitigate the signal attenuation or to providedirectional beams in order to best utilize the channel, the use ofbeamforming with respect to high frequency carriers (e.g.,millimeter-wave) in some wireless communication systems (e.g., manycellular communication system configurations) presents its ownchallenges. For example, the unique challenges of heavy path-loss facedby millimeter-wave systems suggests techniques such as analogbeamforming. However, the use of several wideband power amplifiers in asystem implementing analog beamforming techniques can introduce issueswith respect to the communication system signals, such as issuesregarding peak-to-average power ratio (PAPR), spectral efficiency, etc.

Accordingly, embodiments of wireless communication devices herein areadapted to implement adaptive waveform selection, such as to providedynamic selection between use of SC-FDM and OFDM, for the communicationsignals transmitted by the wireless communication devices. For example,operation according to embodiments provides for use of a waveform designthat minimizes PAPR, such as SC-FDM, as well as a waveform design thatprovides higher spectral efficiency, such as OFDM, for scenarios thatare not power-limited and higher PAPR is acceptable.

In an aspect of the disclosure, a method for adaptive waveform selectionfor signal transmission in a wireless communication system is provided.For example, a method can include analyzing, by a wireless device of thewireless communication system, one or more parameters of a wirelesscommunication scheduling grant. The method can further include selectinga waveform from a plurality of waveforms for the signal transmissionbased on analyzing one or more parameters of the wireless communicationscheduling grant.

In an additional aspect of the disclosure, an apparatus for adaptivewaveform selection for signal transmission in a wireless communicationsystem is provided. The apparatus can include means for analyzing, by awireless device of the wireless communication system, one or moreparameters of a wireless communication scheduling grant. The apparatuscan further include means for selecting a waveform from a plurality ofwaveforms for the signal transmission based on analyzing one or moreparameters of the wireless communication scheduling grant.

In an additional aspect of the disclosure, a non-transitorycomputer-readable medium having program code recorded thereon isprovided. The program code can include code for causing one or morecomputers to analyze one or more parameters of a wireless communicationscheduling grant. The program code can further include code for causingone or more computers to select a waveform from a plurality of waveformsfor the signal transmission based on analyzing one or more parameters ofthe wireless communication scheduling grant.

In an additional aspect of the disclosure, an apparatus for adaptivewaveform selection for signal transmission in a wireless communicationsystem is provided. The apparatus includes at least one processor, and amemory coupled to the processor. The at least one processor can beconfigured to analyze one or more parameters of a wireless communicationscheduling grant. The at least one processor can further be configuredto select a waveform from a plurality of waveforms for the signaltransmission based on analyzing one or more parameters of the wirelesscommunication scheduling grant.

Other aspects, features, and embodiments of the present invention willbecome apparent to those of ordinary skill in the art, upon reviewingthe following description of specific, exemplary embodiments of thepresent invention in conjunction with the accompanying figures. Whilefeatures of the present invention may be discussed relative to certainembodiments and figures below, all embodiments of the present inventioncan include one or more of the advantageous features discussed herein.In other words, while one or more embodiments may be discussed as havingcertain advantageous features, one or more of such features may also beused in accordance with the various embodiments of the inventiondiscussed herein. In similar fashion, while exemplary embodiments may bediscussed below as device, system, or method embodiments it should beunderstood that such exemplary embodiments can be implemented in variousdevices, systems, and methods.

BRIEF DESCRIPTION OF THE DRAWINGS

A further understanding of the nature and advantages of the presentdisclosure may be realized by reference to the following drawings. Inthe appended figures, similar components or features may have the samereference label. Further, various components of the same type may bedistinguished by following the reference label by a dash and a secondlabel that distinguishes among the similar components. If just the firstreference label is used in the specification, the description isapplicable to any one of the similar components having the same firstreference label irrespective of the second reference label.

FIG. 1 is a block diagram illustrating details of a wirelesscommunication system according to some embodiments of the presentdisclosure.

FIG. 2 is a block diagram conceptually illustrating a design of a basestation/eNB and a UE configured according to some embodiments of thepresent disclosure.

FIG. 3 is a flow diagram showing operation in accordance with someembodiments of the present disclosure.

DETAILED DESCRIPTION

The detailed description set forth below, in connection with theappended drawings, is intended as a description of various possibleconfigurations and is not intended to limit the scope of the disclosure.Rather, the detailed description includes specific details for thepurpose of providing a thorough understanding of the inventive subjectmatter. It will be apparent to those skilled in the art that thesespecific details are not required in every case and that, in someinstances, well-known structures and components are shown in blockdiagram form for clarity of presentation.

This disclosure relates generally to providing or participating incommunication as between two or more wireless devices in one or morewireless communications systems, also referred to as wirelesscommunications networks. In various embodiments, the techniques andapparatus may be used for wireless communication networks such as codedivision multiple access (CDMA) networks, time division multiple access(TDMA.) networks, frequency division multiple access (FDMA) networks,orthogonal FDMA (OFDMA) networks, single-carrier FDMA (SC-FDMA)networks, LTE networks, GSM networks, as well as other communicationsnetworks. As described herein, the terms “networks” and “systems” may beused interchangeably according to the particular context.

A CDMA network may implement a radio technology such as universalterrestrial radio access (UTRA), cdma2000, and the like. UTRA includeswideband-CDMA (W-CDMA) and low chip rate (LCR). CDMA2000 covers 1S-2000,IS-95, and IS-856 standards.

A TDMA network may implement a radio technology such as Global Systemfor Mobile Communications (GSM). 3GPP defines standards for the GSM EDGE(enhanced data rates for GSM evolution) radio access network. (RAN),also denoted as GERAN. GERAN is the radio component of GSM/EDGE,together with the network that joins the base stations (for example, theAter and Abis interfaces) and the base station controllers (Ainterfaces, etc.). The radio access network represents a component of aGSM network, through which phone calls and packet data are routed fromand to the public switched telephone network (PSTN) and Internet to andfrom subscriber handsets, also known as user terminals or userequipments (UEs). A mobile phone operator's network may comprise one ormore GERANs, which may be coupled with UTRANs in the case of a UMTS/GSMnetwork. An operator network may also include one or more LTE networks,and/or one or more other networks. The various different network typesmay use different radio access technologies (RATs) and radio accessnetworks (RANs).

An OFDMA network may implement a radio technology such as evolved UTRA(E-UTRA), IEEE 802.11, IEEE 802.16, IEEE 802.20, flash-OFDM and thelike. UTRA, E-UTRA, and GSM are part of universal mobiletelecommunication system (UMTS). In particular, long term evolution(LTE) is a release of UMTS that uses E-UTRA. UTRA, E-UTRA, GSM, UMTS andLTE are described in documents provided from an organization named “3rdGeneration Partnership Project” (3GPP), and cdma.2000 is described indocuments from an organization named “3rd Generation Partnership Project2” (3GPP2). These various radio technologies and standards are known orare being developed. For example, the 3rd Generation Partnership Project(3GPP) is a collaboration between groups of telecommunicationsassociations that aims to define a globally applicable third generation(3G) mobile phone specification. 3GPP long term evolution (LTE) is a3GPP project aimed at improving the universal mobile telecommunicationssystem (UMTS) mobile phone standard. The 3GPP may define specificationsfor the next generation of mobile networks, mobile systems, and mobiledevices. For clarity, certain aspects of the apparatus and techniquesmay be described below for LTE implementations or in an LTE-centric way,and LTE terminology may be used as illustrative examples in portions ofthe description below; however, the description is not intended to belimited to LTE applications. Indeed, the present disclosure is concernedwith shared access to wireless spectrum between networks using differentradio access technologies or radio air interfaces.

A new carrier type based on LTE/LTE-A including unlicensed spectrum hasalso been suggested that can be compatible with carrier-grade WiFi,making LTE/LTE-A with unlicensed spectrum an alternative to WiFi.LTE/LTE-A, when operating in unlicensed spectrum, may leverage LTEconcepts and may introduce some modifications to physical layer (PHY)and media access control (MAC) aspects of the network or network devicesto provide efficient operation in the unlicensed spectrum and meetregulatory requirements. The unlicensed spectrum used may range from aslow as several hundred Megahertz (MHz) to as high as tens of Gigahertz(GHz), for example. In operation, such LTE/LTE-A networks may operatewith any combination of licensed or unlicensed spectrum depending onloading and availability. Accordingly, it may be apparent to one ofskill in the art that the systems, apparatus and methods describedherein may be applied to other communications systems and applications.

System designs may support various time-frequency reference signals forthe downlink and uplink to facilitate beamforming and other functions. Areference signal is a signal generated based on known data and may alsobe referred to as a pilot, preamble, training signal, sounding signal,and the like. A reference signal may be used by a receiver for variouspurposes such as channel estimation, coherent demodulation, channelquality measurement, signal strength measurement, and the like. MIMOsystems using multiple antennas generally provide for coordination ofsending of reference signals between antennas; however, LTE systems donot in general provide for coordination of sending of reference signalsfrom multiple base stations or eNBs.

In some implementations, a system may utilize time division duplexing(TDD). For TDD, the downlink and uplink share the same frequencyspectrum or channel, and downlink and uplink transmissions are sent onthe same frequency spectrum. The downlink channel response may thus becorrelated with the uplink channel response. Reciprocity may allow adownlink channel to be estimated based on transmissions sent via theuplink. These uplink transmissions may be reference signals or uplinkcontrol channels (which may be used as reference symbols afterdemodulation). The uplink transmissions may allow for estimation of aspace-selective channel via multiple antennas.

In LTE implementations, orthogonal frequency division multiplexing(OFDM) is used for the downlink—that is, from a base station, accesspoint or eNodeB (eNB) to a user terminal or UE. Use of OFDM meets theLTE requirement for spectrum flexibility and enables cost-efficientsolutions for very wide carriers with high peak rates, and is awell-established technology. For example, OFDM is used in standards suchas IEEE 802.11a/g, 802.16, High Performance Radio LAN-2 (HIPERLAN-2,wherein LAN stands for Local Area Network) standardized by the European‘Telecommunications Standards Institute (ETSI), Digital VideoBroadcasting (DVB) published by the Joint Technical Committee of ETSI,and other standards.

Time frequency physical resource blocks (also denoted here in asresource blocks or

“RBs” for brevity) may be defined in OFDM systems as groups of transportcarriers (e.g. sub-carriers) or intervals that are assigned to transportdata. The RBs are defined over a time and frequency period. Resourceblocks are comprised of time-frequency resource elements (also denotedhere in as resource elements or “REs” for brevity), which may be definedby indices of time and frequency in a slot. Additional details of LTERBs and REs are described in the 3GPP specifications, such as, forexample, 3GPP ‘TS 36.211.

UMTS LTE supports scalable carrier bandwidths from 20 MHz down to 1.4MHZ. In LTE, an RB is defined as 12 sub-carriers when the subcarrierbandwidth is 15 kHz, or 24 sub-carriers when the sub-carrier bandwidthis 7.5 kHz. In an exemplary implementation, in the time domain there isa defined radio frame that is 10 ms long and consists of 10 subframes of1 millisecond (ms) each. Every subframe consists of 2 slots, where eachslot is 0.5 ms. The subcarrier spacing in the frequency domain in thiscase is 15 kHz. Twelve of these subcarriers together (per slot)constitute an RB, so in this implementation one resource block is 180kHz. Six Resource blocks fit in a carrier of 1.4 MHz and 100 resourceblocks fit in a carrier of 20 MHz.

FIG. 1 shows a wireless network 100 for communication according to someembodiments. While discussion of the technology of this disclosure isprovided relative to an LTE-A network (shown in FIG. 1), this is forillustrative purposes. Principles of the technology disclosed can beused in other network deployments, including fifth generation networks.As appreciated by those skilled in the art, components appearing in FIG.1 are likely to have related counterparts in other network arrangements.

Turning back to FIG. 1, the wireless network 100 includes a number ofevolved node Bs (eNBs) 105 and other network entities. An eNB may be astation that communicates with the UEs and may also be referred to as abase station, a node B, an access point, and the like. Each eNB 105 mayprovide communication coverage for a particular geographic area. In3GPP, the term “cell” can refer to this particular geographic coveragearea of an eNB and/or eNB subsystem serving the coverage area, dependingon the context in which the term is used.

An eNB may provide communication coverage for a macro cell or a smallcell, such as a pico cell or a femto cell, and/or other types of cell. Amacro cell generally covers a relatively large geographic area (e.g.,several kilometers in radius) and may allow unrestricted access by UEswith service subscriptions with the network provider. A small cell, suchas a pico cell, would generally cover a relatively smaller geographicarea and may allow unrestricted access by UEs with service subscriptionswith the network provider. A small cell, such as a femto cell, wouldalso generally cover a relatively small geographic area (e.g., a home)and, in addition to unrestricted access, may also provide restrictedaccess by UEs having an association with the femto cell (e.g., UEs in aclosed subscriber group (CSG), UEs for users in the home, and the like).An eNB for a macro cell may be referred to as a macro eNB. An eNB for asmall cell may be referred to as a small cell eNB, a pico eNB, femto eNBor a home eNB. In the example shown in FIG. 1, the eNBs 105 a, 105 b and105 c are macro eNBs for the macro cells 110 a, 110 b and 110 c,respectively. The eNBs 105 x, 105 y, and 105 z are small cell eNBs,which may include pico or femto eNBs that provide service to small cells110 x, 110 y, and 110 z, respectively. An eNB may support one ormultiple (e.g., two, three, four, and the like) cells.

The wireless network 100 may support synchronous or asynchronousoperation. For synchronous operation, the eNBs may have similar frametiming, and transmissions from different eNBs may be approximatelyaligned in time. For asynchronous operation, the eNBs may have differentframe timing, and transmissions from different eNBs may not be alignedin time.

The UEs 115 are dispersed throughout the wireless network 100, and eachUE may be stationary or mobile. It should be appreciated that, althougha mobile apparatus is commonly referred to as user equipment (UE) instandards and specifications promulgated by the 3rd Generation.Partnership Project (3GPP), such apparatus may also be referred to bythose skilled in the art as a mobile station (MS), a subscriber station,a mobile unit, a subscriber unit, a wireless unit, a remote unit, amobile device, a wireless device, a wireless communications device, aremote device, a mobile subscriber station, an access terminal (AT), amobile terminal, a wireless terminal, a remote terminal, a handset, aterminal, a user agent, a mobile client, a client, or some othersuitable terminology. Within the present document, a “mobile” apparatusor UE need not necessarily have a capability to move, and may bestationary. Some non-limiting examples of a mobile apparatus, such asmay comprise embodiments of one or more of the UEs 115, include amobile, a cellular (cell) phone, a smart phone, a session initiationprotocol (SIP) phone, a laptop, a personal computer (PC), a notebook, anetbook, a smart book, a tablet, and a personal digital assistant (PDA).A mobile apparatus may additionally be an “Internet of things” (IoT)device such as an automotive or other transportation vehicle, asatellite radio, a global positioning system (GPS) device, a logisticscontroller, a drone, a multi-copter, a quad-copter, a smart energy orsecurity device, a solar panel or solar array, municipal lighting,water, or other infrastructure; industrial automation and enterprisedevices; consumer and wearable devices, such as eyewear, a wearablecamera, a smart watch, a health or fitness tracker, a mammal implantabledevice, gesture tracking device, medical device, a digital audio player(e.g., MP3 player), a camera, a game console, etc.; and digital home orsmart home devices such as a home audio, video, and multimedia device,an appliance, a sensor, a vending machine, intelligent lighting, a homesecurity system, a smart meter, etc. A mobile apparatus, such as the UEs115, may be able to communicate with macro eNBs, pico eNBs, femto eNBs,relays, and the like. In FIG. 1, a lightning bolt (e.g., communicationlinks 125) indicates wireless transmissions between a UE and a servingeNB, which is an eNB designated to serve the UE on the downlink and/oruplink, or desired transmission between eNBs. Although the backhaulcommunication 134 is illustrated as wired backhaul communications thatmay occur between eNBs, it should be appreciated that backhaulcommunications may additionally or alternatively be provided by wirelesscommunications.

LTE/-A utilizes orthogonal frequency division multiplexing (OFDM) on thedownlink and single-carrier frequency division multiplexing (SC-FDM) onthe uplink. OFDM and SC-FDM partition the system bandwidth into multiple(K) orthogonal subcarriers, which are also commonly referred to astones, bins, or the like. Each subcarrier may be modulated with data. Ingeneral, modulation symbols are sent in the frequency domain with OFDMand in the time domain with SC-FDM. The spacing between adjacentsubcarriers may be fixed, and the total number of subcarriers (K) may bedependent on the system bandwidth. For example, K may be equal to 72,180, 300, 600, 900, and 1200 for a corresponding system bandwidth of1.4, 3, 5, 10, 15, or 20 megahertz (MHz), respectively. The systembandwidth may also be partitioned into sub-bands. For example, asub-band may cover 1.08 MHz, and there may be 1, 2, 4, 8 or 16 sub-bandsfor a corresponding system bandwidth of 1.4, 3, 5, 10, 15, or 20 MHz,respectively.

FIG. 2 shows a block diagram of a design of a base station/eNB 105 and aUE 115, which may be one of the base stations/eNBs and one of the UEs inFIG. 1. For a restricted association scenario, the eNB 105 may be thesmall cell eNB 105 z in FIG. 1, and the UE 115 may be the UE 115 z,which in order to access small cell eNB 105 z, would be included in alist of accessible UEs for small cell eNB 105 z. The eNB 105 may also bea base station of some other type. The eNB 105 may be equipped withantennas 234 a through 234 t, and the UE 115 may be equipped withantennas 252 a through 252 r.

At the eNB 105, a transmit processor 220 may receive data from a datasource 212 and control information from a controller/processor 240. Thecontrol information may be for the PBCH, PCFICH, PHICH, PDCCH, etc. Thedata may be for the PDSCH, etc. The transmit processor 220 may process(e.g., encode and symbol map) the data and control information to obtaindata symbols and control symbols, respectively. The transmit processor220 may also generate reference symbols, e.g., for the PSS, SSS, andcell-specific reference signal. A transmit (TX) multiple-inputmultiple-output (MIMO) processor 230 may perform spatial processing(e.g., precoding) on the data symbols, the control symbols, and/or thereference symbols, if applicable, and may provide output symbol streamsto the modulators (MODS) 232 a through 232 t. Each modulator 232provides a communication interface, as may process a respective outputsymbol stream (e.g., for OFDM, etc.) to obtain an output sample stream.Each modulator 232 may additionally or alternatively process (e.g.,convert to analog, amplify, filter, and upconvert) the output samplestream to obtain a downlink signal. Downlink signals from modulators 232a through 232 t may be transmitted via the antennas 234 a through 234 t,respectively.

At the UE 115, the antennas 252 a through 252 r may receive the downlinksignals from the eNB 105 and may provide received signals to thedemodulators (DEMODs) 254 a through 254 r, respectively. Eachdemodulator 254 provides a communication interface as may condition(e.g., filter, amplify, downconvert, and digitize) a respective receivedsignal to obtain input samples. Each demodulator 254 may further processthe input samples (e.g., for OFDM, etc.) to obtain received symbols. AMIMO detector 256 may obtain received symbols from all the demodulators254 a through 254 r, perform MIMO detection on the received symbols ifapplicable, and provide detected symbols. A receive processor 258 mayprocess (e.g., demodulate, deinterleave, and decode) the detectedsymbols, provide decoded data for the UE 115 to a data sink 260, andprovide decoded control information to a controller/processor 280.

On the uplink, at the UE 115, a transmit processor 264 may receive andprocess data (e.g., for the PUSCH) from a data source 262 and controlinformation (e.g., for the PUCCH) from the controller/processor 280. Thetransmit processor 264 may also generate reference symbols for areference signal. The symbols from the transmit processor 264 may beprecoded by a TX MIMO processor 266 if applicable, further processed bythe modulators 254 a through 254 r (e.g., for SC-FDM, etc.), andtransmitted to the eNB 105. At the eNB 105, the uplink signals from theUE 115 may be received by the antennas 234, processed by thedemodulators 232, detected by a MIMO detector 236 if applicable, andfurther processed by a receive processor 238 to obtain decoded data andcontrol information sent by the UE 115. The processor 238 ay provide thedecoded data to a data sink 239 and the decoded control information tothe controller/processor 240.

The controllers/processors 240 and 280 may direct the operation at theeNB 105 and the UE 115, respectively. The controller/processor 240and/or other processors and modules at the eNB 105 may perform or directthe execution of various processes for the techniques described herein.The controllers/processor 280 and/or other processors and modules at theUE 115 may also perform or direct the execution of the functional blocksillustrated in FIG. 4, and/or other processes for the techniquesdescribed herein. The memories 242 and 282 may store data and programcodes for the eNB 105 and the UE 115, respectively. A scheduler 244 mayschedule UEs for data transmission on the downlink and/or uplink.

Referring again to FIG. 1, in operation according to aspects of thedisclosure, various of the communication devices (e.g., one or more ofeNBs 105 and/or UEs 115) of wireless network 100 are adapted to utilizehigh frequency carriers, such as millimeter-wave (e.g., one or morefrequency band within 28 GHz-300 GHz), for implementing wirelesscommunications. Circuitry of the communication devices participating insuch high frequency communications may implement beamforming withrespect to the high frequency wireless signals, such as to accommodatesignal attenuation associated with the use of high frequency carriers,to facilitate increased channel capacity, to avoid or mitigateinterference, etc. For example, one of eNB 105 may implement beamformingwith respect to signal transmissions (i.e., downlink transmissionbeamforming) and/or receiving signals (i.e., uplink receivingbeamforming). Additionally or alternatively, one or more of UEs 115 mayimplement beamforming with respect to signal transmissions (i.e., uplinktransmission beamforming) and/or receiving signals (i.e., downlinkreceiving beamforming).

As mentioned above, beamforming can be utilized in varying manners. Forexample, signal transmission beamforming may be provided through MIMOprocessor 230 performing precoding (e.g., under control ofcontroller/processor 240) on signals to be transmitted by eNB 105 (e.g.,downlink signals) and/or MIMO processor 266 performing precoding (e.g.,under control of controller/processor 280) on signals to be transmittedby UE 115 (e.g., uplink signals). Similarly, receive beamforming may beprovided through MIMO detector 236 performing spatial decoding (e.g.,under control of controller/processor 240) on signals received by eNB105 (e.g., uplink signals) and/or MIMO detector 266 performing spatialdecoding (e.g., under control of controller/processor 280) on signalsreceived by UE 115 (e.g., downlink signals).

Embodiments of eNBs 105 and/or UEs 115 implement analog beamforming,such as to address heavy path-loss associated with the use of highfrequency carriers. Accordingly, the aforementioned transmissionbeamforming may be provided through MIMO processor 230 utilizing abeamforming network (e.g., Butler matrix, network of phase shifters andattenuators, etc.) providing relative phase shift and signal powerweighting (e.g., under control of controller/processor 240) with respectto the signals provided to the antenna elements of antennas 234 athrough 234 t to be transmitted by eNB 105 (e.g., downlink signals)and/or MIMO processor 266 utilizing a beamforming network providingrelative phase shift and signal power weighting (e.g., under control ofcontroller/processor 280) with respect to the signals provided to theantenna elements of antennas 252 a through 252 r to be transmitted by UE115 (e.g., uplink signals). Similarly, receive beamforming may beprovided through MIMO detector 236 utilizing a beamforming networkproviding relative phase shift and signal power weighting (e.g., undercontrol of controller/processor 240) with respect to the signalsprovided by the antenna elements of antennas 234 a through 234 treceived by eNB 105 (e.g., uplink signals) and/or MIMO detector 256utilizing a beamforming network providing relative phase shift andsignal power weighting (e.g., under control of controller/processor 280)with respect to the signals provided by the antenna elements of antennas252 a through 252 r received by UE 115 (e.g., downlink signals).

Use of analog beamforming techniques may include the use of severalwideband power amplifiers (e.g., transmit power amplifiers of MIMOprocessors 230 and/or 266). In a multicarrier system, if each componentcarrier goes through a separate power amplifier (PA), then thepeak-to-average power ratio (PAPR) need be considered only on aper-carrier basis. However, especially in high frequency (e.g.,millimeter-wave) systems, where several PAs are needed to facilitateanalog beamforming, a common PA may be utilized for a plurality of thecomponent carriers (e.g., all component carriers), and thus the PAPR ofthe combined waveform from all carriers should be considered.

The PAPR advantage of SC-FDM over OFDM reduces as the number ofcomponent carriers increases. This is because the carriers may not becontiguous, and even if the carriers are contiguous, the DiscreteFourier Transform-spreading (DFT-spreading) operation does not spanmultiple carriers to avoid prohibitively large DFT-size. Similarly, ifMIMO operation is allowed with non-diagonal preceding, the combining ofthe MIMO layers erodes the PAPR advantage of SC-FDM. On the other hand,the link performance advantage of OFDM over SC-FDM is higher at highsignal-to-noise ratio (SNR) and lower at low SNR.

Accordingly, in accordance with aspects of the disclosure, devices ofwireless network 100 are adapted to implement adaptive waveformselection. Selection in dynamic fashion enables real-time adjustmentsbased on real-time operating circumstances. In some scenarios, adaptivewaveform selection includes dynamic selection between use of SC-FDM andOFDM, for communication signals transmitted by one or more wirelessdevices (e.g., any or all of eNBs 105 and/or UEs 115). For example,operation according to embodiments may provide for use of a waveformdesign that minimizes PAPR, such as SC-FDM, as well as a waveform designthat provides higher spectral efficiency, such as OFDM, for scenariosthat are not power-limited and the higher PAPR is acceptable.

Exemplary implementations of adaptive waveform selection are describedherein with reference to the use of high frequency carriers, such asmillimeter-wave carriers. Yet it should be appreciated that adaptivewaveform selection provided according to the concepts herein mayadditionally or alternatively be utilized with respect to devicescommunicating using other frequencies, such as sub-6 GHz frequencies.

In operation according to aspects of the disclosure, one or morewireless devices (e.g., any or all of eNBs 105 and/or UEs 115)communicating via a wireless link (e.g., communication links 125)operate to analyze attributes of the wireless communications (e.g.,parameters of a scheduling grant) and select an appropriate waveformfrom a plurality of possible waveforms (e.g., SC-FDM, OFDM, etc.) forthe wireless communications. For example, logic of controller/processor240 and/or controller/processor 280 may operate to analyze variousattributes associated with wireless communications conducted by arespective one of eNB 105 and UE 115 to select a waveform from aplurality of waveforms and control corresponding ones of modulators 232a through 232 t (eNB 105) and/or modulators 252 a through 252 r (UE 115)to process a respective signal stream for the selected waveform (e.g.,SC-FDM, OFDM, etc.). Attributes associated with the wirelesscommunications analyzed according to embodiments may include one or moreof the number of component carriers on which data is transmitted and/oron each carrier, the modulation order, number of spatial layers, and/orspectral efficiency of the modulation-and-coding format for thetransmission, associated with the wireless link transmissions. Inoperation according to some implementations the control logic may, forexample, select OFDM in scenarios of high SNR (e.g., SNR determined tomeet or exceed a threshold allowing high order modulation, such as 64QAM, SNR of 10 or 15 dB), more than a few carriers (e.g., at least athreshold number of carriers, such as 2 or more carriers or 3 or morecarriers, as may be determined based on one or more scheduling grantsthat are signaled on one or more carriers), and/or MIMO (multiplespatial layers). Conversely, the control logic of some implementationsmay select SC-FDM in scenarios of few carriers (e,g., less than athreshold number of carriers, such as 1 carrier or 2 carriers), low SNR(e.g., at or below a threshold SNR requiring low order modulation, suchas less than 64 QAM, or SNR less than 10 or 15 dB), and/or single-layertransmission.

Embodiments may initiate use of a selected waveform without explicitlysignaling a corresponding wireless device of the communication link.Signaling of selection of a waveform for data transmission may beprovided implicitly according to sonic implementations, such as by theselection of a particular waveform for data transmission beingdetermined by a receiving device based implicitly on the variousattributes associated with the wireless communications. For example,particular attribute values and/or combinations of attribute values(e.g., different combinations of grant parameters) may each be mapped toan appropriate one of the possible waveform selections of a plurality ofwaveform selections. Accordingly, the attributes or combinations ofattributes for one or more grant parameters analyzed according toembodiments may be compared to a database or other information providinga mapping of attribute values and/or combinations of attribute values toparticular waveform selections in order to provide waveform selectioninformation (e.g., identify a particular waveform for use in view of theanalyzed grant parameters via the mapping between attribute values andwaveform selections). An example of a grant parameter attribute value towaveform selection information mapping is shown in the table below. Itshould be appreciated that the particular values illustrated for theexemplary waveform selections in the table below are merely examples andembodiments may utilize different values, different waveform selections,and/or different parameter attributes. Moreover, although the tablebelow shows a one-to-one mapping of parameter attributes to waveformselection for simplicity, it should be appreciated that variouscombinations of parameter values (e.g., a combination of SNR value andnumber of carriers having particular values for selection of aparticular waveform) may be utilized in a mapping implemented accordingto embodiments herein. The mapping as may be utilized according toembodiments may be fixed (e.g., established by specification or anadopted standard). However, the mapping may be dynamic (e.g., signaledsemi-statically in system information messages or in configurationmessages, wherein the mapping of parameters to waveforms can varysemi-statically), according to some embodiments.

Scheduling Grant Parameter Attribute Waveform Selection SNR ≥ 10 dB OFDMSNR < 10 dB SC-FDM Number of Carriers > 2 OFDM Number of Carriers ≤ 2SC-FDM MIMO OFDM Single layer transmission SC-FDM

Additionally or alternatively, implementations herein may provide forexplicit signaling in association with the adaptive waveform selection.Such explicit signaling may, for example, be semi-static (e.g., based onsystem information messages or higher layer reconfiguration messages) ormore dynamic (e.g., based on a waveform-selection field in thescheduling grants). For example, explicit signaling of selection of awaveform for data transmission may he provided using a field in thescheduling grant for that transmission.

In operation according to some implementations, certain combinations ofwaveform selection and other grant parameters may be designated asinvalid, and thus the corresponding grant may be rejected. Such invalidcombinations of waveform selection and other parameters may be based onone or more scheduling grants for transmission on one or more componentcarriers, and the grants themselves may be received on one or morecomponent carriers. For example, a combination of waveform selection andgrant parameters may be designated as invalid if scheduling grantsreceived for transmission on two component carriers indicate twodifferent types of waveforms and both grants may be rejected. As anotherexample of a combination of waveform selection and grant parametersdesignated as invalid according to embodiments, a high modulation ordersuch as 256 QAM could be enforced to always use a particular waveformsuch as OFDM, and thus grants assigning such a high modulation order toanother waveform (e.g., SC-FDM) may be rejected.

It should be appreciated that adaptive waveform selection in accordancewith the concepts herein may be applied to downlink waveform selection,uplink waveform selection, or both downlink and uplink waveformselection. On a downlink provided by a eNB or other base station servinga plurality of devices (e.g., multiple UEs) all the frequency divisionmultiplexed transmissions may be passed through a common PA at the basestation and thus an implementation herein may use the same waveform foreach of these transmissions. In operation according to an implementationin accordance with this example, downlink broadcast control channels maybe time division multiplexed with a data channel in order to allowdynamic waveform selection for downlink data channel. The downlinkscheduler may be optimized such that wireless devices for which the samedownlink waveform is selected or otherwise preferred are scheduledtogether by FDM. In operation according to some implementations,downlink scheduling grants may be transmitted using a fixed waveform,such as to avoid the complexity of multiple waveform hypothesis decodingof the grants at the corresponding wireless device. These grants may,for example, be carried on a control channel (e.g., PDCCH in LTE) thatis time division multiplexed with downlink data.

Adaptive waveform selection may not only be utilized with respect to anestablished communication link, but additionally or alternatively beutilized with respect to initially establishing a communication link. Asan example of the use of adaptive waveform selection when initiallyestablishing a communication link, operation will be described withreference to a random access procedure (e.g., a random access procedurefor a random access channel (RACH), such as the RACH channel specifiedin LTE), wherein it may be beneficial to use the most efficient waveformfor communication according to the concepts herein. In such a randomaccess procedure, UE 115 may transmit a message (e.g., a physical randomaccess channel (PRACH) sequence) to eNB 105, UE 115 may receive aresponse (Msg2) from eNB 105, UE 115 then may transmit another message(Msg3) to eNB 105, and thereafter UE 115 may receive an additionalmessage (Msg4) from eNB 105 to complete the RACH procedure.

In operation of adaptive waveform selection of embodiments during theforegoing random access procedure, the waveform to be used fortransmission of the message to initiate the random access procedure(e.g., the aforementioned PRACH sequence) may be fixed, such as to usethe same waveform (e.g., SC-FDM) for all such messages. Alternatively,the waveform used for transmitting this message may be adaptivelychanged, such as may be determined by a receiver implementing a multiplewaveform analysis technique as described below. Similarly, the waveformto be used for uplink transmission (Msg3, or message-3 in LTE) that ismade after receiving the random access response (Msg2, or RAR, ormessage-2 in LTE) may be fixed or may be determined dynamically, such asbased on one or more attributes of the wireless communications. Forexample, the waveform to be used for the uplink transmission may bedynamically selected based upon system information present in broadcastdownlink messages (e.g., system information blocks (SIBs)), informationin a response message (e.g., msg2 or RAR message), the PRACH sequenceused for initial access (e.g., each PRACH sequence may be associatedwith a particular waveform, whereby different PRACH sequences may beutilized with respect to OFDM, SC-FDM, etc.), wireless devicemeasurements (e.g., UE measurements of path-loss), and/or the like.

It should be appreciated that measurements made by one wireless device(e.g., UE 115) for selection of a waveform may not be known to anotherwireless device (e.g., eNB 105). Accordingly, if waveform selection by afirst wireless device is based on parameters not known to secondwireless device, this second wireless device may operate to attempt toreceive a message transmission (e.g., Msg3 or message-3) separatelyassuming each possible waveform choice. Such a multiple waveformanalysis technique, wherein processing of the receive message may beperformed a plurality of times before the appropriate waveform isidentified, may be suitable for some configurations of wireless devices(e.g., base stations having robust resources, connection to power mains,etc.) while being unsuitable for other configurations of wirelessdevices (e.g., UEs having more limited resources, operating on batterypower, etc.). Accordingly, although operation with respect to one linkdirection (e.g., uplink) may provide for determining the waveformthrough multiple attempts to receive the message, operation with respectto the other link direction (e.g., downlink) may provide for determiningthe waveform without invoking such multiple attempts to receive themessage (e.g., by using a fixed waveform, by providing explicitsignaling regarding the waveform, etc.). For example, when a downlinkdata channel uses adaptive waveform selection based on an explicitindication in downlink scheduling grant, the downlink control channelscarrying the scheduling grants and broadcast information may be timedivision multiplexed with downlink data channel and use a fixedwaveform. As another example, when a downlink data channel uses adaptivewaveform selection based on an explicit indication in downlinkscheduling grant, the random access response (e.g., Msg2 or RAR) and theadditional message (e.g., Msg4 or message-4 in LTE) may use a fixedwaveform.

Referring now to FIG. 3, flow 300 illustrating operation of an adaptivewaveform selection technique implemented according to aspects of thepresent disclosure is shown. The processes of flow 300 may, for example,be implemented by adaptive waveform selection logic of eNB 105 and/or UE115 (e.g., logic of controller/processor 240 and/or controller/processor280). Adaptive waveform selection logic (or some portion thereof) ofembodiments may, for example, be provided as one or more instructionsets (e.g., software codes and/or firmware codes, such as may be storedby memory 242 and/or memory 282) executed by controller/processor 240and/or controller processor 280 to form logic circuits providingoperation as described herein. Additionally or alternatively, adaptivewaveform selection logic (or some portion thereof) of embodiments may beprovided as circuits of one or more hardware devices or electronicscomponents (e.g., digital signal processor (DST), application specificintegrated circuit (ASIC), field programmable gate array (FPGA),discrete gate or transistor logic, etc.) to form logic circuitsproviding operation as described herein.

At block 301 of the illustrated implementation, one or more attributesof wireless communications are analyzed by adaptive waveform selectionlogic (e.g., adaptive waveform selection logic implemented bycontroller/processor 240 of eNB 105 and/or adaptive waveform selectionlogic implemented by controller/processor 280 of UE 115) of embodiments.For example, parameters of a scheduling grant, such as may include oneor more of the number of component carriers on which data is transmittedand/or on each carrier, the modulation order, number of spatial layers,and/or spectral efficiency of the modulation-and-coding format for thetransmission, associated with the wireless link transmissions.Additionally or alternatively, explicit signaling regarding a waveformfor the wireless communication may be analyzed. For example, systeminformation messages or higher layer reconfiguration messages may beanalyzed for explicit waveform signaling. Similarly, awaveform-selection field in the wireless communication scheduling grantmay be analyzed for explicit waveform signaling.

At block 302 of the illustrated implementation, a waveform forcommunication is selected from a plurality of waveforms by adaptivewaveform selection logic (e.g., adaptive waveform selection logicimplemented by controller/processor 240 of eNB 105 and/or adaptivewaveform selection logic implemented by controller/processor 280 of UE115) of embodiments based on information provided by the analysis ofblock 301. For example, an appropriate waveform may be selected from aplurality of possible waveforms that include a SC-FDM waveform designand an OFDM waveform design. Thereafter, the selected waveform may beutilized in wireless communications performed according to the wirelesscommunication scheduling grant.

Those of skill in the art would understand that information and signalsmay be represented using any of a variety of different technologies andtechniques. For example, data, instructions, commands, information,signals, bits, symbols, and chips that may be referenced throughout theabove description may be represented by voltages, currents,electromagnetic waves, magnetic fields or particles, optical fields orparticles, or any combination thereof.

The functional blocks and modules in FIGS. 2 and 3 may compriseprocessors, electronics devices, hardware devices, electronicscomponents, logical circuits, memories, software codes, firmware codes,etc., or any combination thereof.

Those of skill would further appreciate that the various illustrativelogical blocks, modules, circuits, and algorithm steps described inconnection with the disclosure herein may be implemented as electronichardware, computer software, or combinations of both. To clearlyillustrate this interchangeability of hardware and software, variousillustrative components, blocks, modules, circuits, and steps have beendescribed above generally in terms of their functionality. Whether suchfunctionality is implemented as hardware or software depends upon theparticular application and design constraints imposed on the overallsystem. Skilled artisans may implement the described functionality invarying ways for each particular application, but such implementationdecisions should not be interpreted as causing a departure from thescope of the present disclosure. Skilled artisans will also readilyrecognize that the order or combination of components, methods, orinteractions that are described herein are merely examples and that thecomponents, methods, or interactions of the various aspects of thepresent disclosure may be combined or performed in ways other than thoseillustrated and described herein.

The various illustrative logical blocks, modules, and circuits describedin connection with the disclosure herein may be implemented or performedwith a general-purpose processor, a DSP, an ASIC, a FPGA or otherprogrammable logic device, discrete gate or transistor logic, discretehardware components, or any combination thereof designed to perform thefunctions described herein. A general-purpose processor may be amicroprocessor, but in the alternative, the processor may be anyconventional processor, controller, microcontroller, or state machine. Aprocessor may also be implemented as a combination of computing devices,e.g., a combination of a DSP and a microprocessor, a plurality ofmicroprocessors, one or more microprocessors in conjunction with a DSPcore, or any other such configuration.

The steps of a method or algorithm described in connection with thedisclosure herein may be embodied directly in hardware, in a softwaremodule executed by a processor, or in a combination of the two. Asoftware module may reside in RAM memory, flash memory, ROM memory,EPROM memory, EEPROM memory, registers, hard disk, a removable disk, aCD-ROM, or any other form of storage medium known in the art. Anexemplary storage medium is coupled to the processor such that theprocessor can read information from, and write information to, thestorage medium. In the alternative, the storage medium may be integralto the processor. The processor and the storage medium may reside in anASIC. The ASIC may reside in a user terminal. In the alternative, theprocessor and the storage medium may reside as discrete components in auser terminal.

In one or more exemplary designs, the functions described may beimplemented in hardware, software, firmware, or any combination thereof.If implemented in software, the functions may be stored on ortransmitted over as one or more instructions or code on acomputer-readable medium. Computer-readable media includes both computerstorage media and communication media including any medium thatfacilitates transfer of a computer program from one place to another.Computer-readable storage media may be any available media that can beaccessed by a general purpose or special purpose computer. By way ofexample, and not limitation, such computer-readable media can compriseRAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic diskstorage or other magnetic storage devices, or any other medium that canbe used to carry or store desired program code means in the form ofinstructions or data structures and that can be accessed by ageneral-purpose or special-purpose computer, or a general-purpose orspecial-purpose processor. Also, a connection may be properly termed acomputer-readable medium. For example, if the software is transmittedfrom a website, server, or other remote source using a coaxial cable,fiber optic cable, twisted pair, or digital subscriber line (DSL), thenthe coaxial cable, fiber optic cable, twisted pair, or DSL, are includedin the definition of medium. Disk and disc, as used herein, includescompact disc (CD), laser disc, optical disc, digital versatile disc(DVD), hard disk, solid state disk, and blu-ray disc where disks usuallyreproduce data magnetically, while discs reproduce data optically withlasers. Combinations of the above should also be included within thescope of computer-readable media.

As used herein, including in the claims, the term “and/or,” when used ina list of two or more items, means that any one of the listed items canbe employed by itself, or any combination of two or more of the listeditems can be employed. For example, if a composition is described ascontaining components A, B, and/or C, the composition can contain Aalone; B alone; C alone; A and B in combination; A and C in combination;B and C in combination; or A, B, and C in combination. Also, as usedherein, including in the claims, “or” as used in a list of itemsprefaced by “at least one of” indicates a disjunctive list such that,for example, a list of “at least one of A, B, or C” means A or B or C orAB or AC or BC or ABC (i.e., A and B and C) or any of these in anycombination thereof.

The previous description of the disclosure is provided to enable anyperson skilled in the art to make or use the disclosure. Variousmodifications to the disclosure will be readily apparent to thoseskilled in the art, and the generic principles defined herein may beapplied to other variations without departing from the spirit or scopeof the disclosure. Thus, the disclosure is not intended to be limited tothe examples and designs described herein but is to be accorded thewidest scope consistent with the principles and novel features disclosedherein.

What is claimed is:
 1. (canceled)
 2. A method for adaptive waveformselection for wireless communication in a wireless communication system,the method comprising: determining, by a wireless device of a wirelesscommunication system, a waveform to use for at least one uplinktransmission associated with a random access channel (RACH) procedure;and transmitting a message corresponding to the RACH procedure based onthe determined waveform.
 3. The method of claim 2, further comprising:performing the RACH procedure comprising: transmitting a first messageof the RACH procedure; and receiving a second message of the RACHprocedure responsive to the first message.
 4. The method of claim 3,wherein the message corresponding to the RACH procedure comprise thefirst message.
 5. The method of claim 4, wherein the first messagecomprises a physical random access channel (PRACH) sequence.
 6. Themethod of claim 3, wherein the second message is responsive to the firstmessage.
 7. The method of claim 6, wherein the second message comprisesa random access response (RAR).
 8. The method of claim 3, furthercomprising: transmitting a third message of the RACH procedure afterreceipt of the second message; and receiving a fourth message of theRACH procedure.
 9. The method of claim 8, wherein the messagecorresponding to the RACH procedure comprises the first message, thethird message, or both.
 10. The method of claim 8, wherein the messagecorresponding to the RACH procedure comprise the third message.
 11. Themethod of claim 8, wherein the fourth message corresponds to completionof the RACH procedure.
 12. An apparatus for adaptive waveform selectionfor wireless communication in a wireless communication system, theapparatus comprising: at least one processor; a memory coupled to the atleast one processor; and a communication interface coupled to the atleast one processor, wherein the at least one processor is configuredto: determine a waveform to use for at least one uplink transmissionassociated with a random access channel (RACH) procedure; and initiatetransmission of a message corresponding to the RACH procedure based onthe determined waveform.
 13. The apparatus of claim 12, wherein thewaveform is one from a plurality of waveforms for uplink signaltransmissions.
 14. The apparatus of claim 13, wherein the plurality ofwaveforms comprise a single-carrier frequency division multiplexing(SC-FDM) waveform design and an orthogonal frequency divisionmultiplexing (OFDM) waveform design.
 15. The apparatus of claim 12,wherein the waveform is determined based on a system information block(SIB), a first message of the RACH procedure, a second message of theRACH procedure, a measurement, or a combination thereof.
 16. Theapparatus of claim 15, wherein the waveform is determined based on thefirst message, the first message comprising a physical random accesschannel (PRACH) sequence.
 17. The apparatus of claim 16, wherein thePRACH sequence corresponds to a single-carrier frequency divisionmultiplexing (SC-FDM) waveform design and an orthogonal frequencydivision multiplexing (OFDM) waveform design.
 18. The apparatus of claim15, wherein the waveform is determined based on the first message, thefirst message comprising a random access response (RAR).
 19. Theapparatus of claim 15, wherein the waveform is determined based on themeasurement.
 20. The apparatus of claim 19, wherein the measurementcomprises a path-loss measurement.
 21. A non-transitorycomputer-readable medium having program code recorded thereon foradaptive waveform selection for wireless communication in a wirelesscommunication system, the program code comprising: program code forcausing one or more computers to: determine a waveform to use for atleast one uplink transmission associated with a random access channel(RACH) procedure; and initiate transmission of a message correspondingto the RACH procedure based on the determined waveform.
 22. Thenon-transitory computer-readable medium of claim 21, wherein thewaveform is determined based on at least one attribute associated withthe RACH procedure.
 23. The non-transitory computer-readable medium ofclaim 22, wherein the at least one attribute comprising systeminformation present in a broadcast downlink message, information in arandom access response message, a physical random access channel (PRACH)sequence, a measurement made by a wireless device, or a combinationthereof.
 24. The non-transitory computer-readable medium of claim 22,wherein the program code comprises program code for causing the one ormore computers to: determine the at least one attribute.
 25. Thenon-transitory computer-readable medium of claim 22, wherein the programcode comprises program code for causing the one or more computers to:analyze the at least one attribute.
 26. The non-transitorycomputer-readable medium of claim 25, wherein the waveform is determinedbased on the analyzed at least one attribute.
 27. An apparatus foradaptive waveform selection for wireless communication in a wirelesscommunication system, the apparatus comprising: means for determining,by a wireless device of a wireless communication system, a waveform touse for at least one uplink transmission associated with a random accesschannel (RACH) procedure; and means for transmitting a messagecorresponding to the RACH procedure based on the determined waveform.28. The apparatus of claim 27, further comprising: means for receivingone or more system information blocks (SIBs).
 29. The apparatus of claim28, wherein the one or more SIBs are received in one or more broadcastdownlink messages.
 30. The apparatus of claim 27, further comprising:initiating the RACH procedure.
 31. The apparatus of claim 27, whereinthe RACH procedure corresponds to a long term evolution (LTE) RACHprocedure.